The Florida citrus industry is having their worst harvest in 73 years, and scientists at the University of Connecticut are stepping in to help.

The poor harvest is in part because of damage from Hurricane Irma, but the devastation started long before that. A disease known as citrus greening has been wreaking havoc for years. UConn researchers are working on a solution.

“Our hope is that we can modify endogenous genes in citrus to create the greening disease’s resistance,” explained University of Connecticut scientist Dr. Yi Li.

Gene editing is often discussed in terms of medical advancements and new health treatments. But gene editing can also benefit the food we eat and agriculture as well. Some of the latest developments are happening in Connecticut.

Florida citrus crops have been falling victim to the greening disease since 2005. The contagious disease is spread by a bacteria found in insects feeding off of citrus crops. The bacteria grows and spreads throughout the trees. But the process is slow – it can take up to five years after a tree is infected for it to show signs of damage. As of today, 75 percent of the Florida citrus crops have been wiped out by this quickly spreading disease that has also made its way to crops in Texas and California.

The UConn scientists are working in conjunction with the University of Florida to find a cure.

“We are basically the technology development lab,” Li said. “And then once we develop the technology people in Florida our collaborators are going to use our technology to genetically modify citrus genome.”

These small, targeted changes to an organism’s original genes produce a specific beneficial result. These genetic alterations can provide plants and animals with beneficial characteristics, just like the disease resistance seen in the citrus crops.

Helping the Florida citrus crop is only part of what’s being done here in the lab. Li and his team have also been implementing their gene editing technique on landscaping products that could soon be used in your own backyard. Their latest project? Slow growing grass.

“We started to breed them to develop these traits that we thought would be beneficial to lawn owners, homeowners, and commercial lawn care people,” explains PhD student Lorenzo Katin-Grazzini, “Such as slow growth to drastically reduce the mowing time that’s needed to really just save cost and time and energy associated with turf grass management.”

Li has also created a genetically modified burning bush, a plant often found in New England that spreads rapidly. Where it grows nothing else can, decreasing the diversity in our forests.

“They either don’t produce seeds or produce very few seeds as such that the birds cannot spread them anymore because there are no seeds,” Li said. “So we hope that those plants are going to be released through horticulture in the next two to three years.”

But the lab at UConn isn’t stopping there.

“I do want to work with more ornamental plants,” Li said. “Particularly invasive plants because I do think that has a huge impact on biodiversity on our environment so if we can use gene editing technology to make that non-invasive that’s what I would like to work on.”

To feed the burgeoning human population, it is vital that the world figures out ways to boost food production.

Increasing crop yields through conventional plant breeding is inefficient – the outcomes are unpredictable and it can take years to decades to create a new strain. On the other hand, powerful genetically modified plant technologies can quickly yield new plant varieties, but their adoption has been controversial. Many consumers and countries have rejected GMO foods even though extensive studies have proved they are safe to consume.

But now a new genome editing technology known as CRISPR may offer a good alternative.

I’m a plant geneticist and one of my top priorities is developing tools to engineer woody plants such as citrus trees that can resist the greening disease, Huanglongbing (HLB), which has devastated these trees around the world. First detected in Florida in 2005, the disease has decimated the state’s $9 billion citrus crop, leading to a 75 percent decline in its orange production in 2017. Because citrus trees take five to 10 years before they produce fruits, our new technique – which has been nominated by many editors-in-chief as one of the groundbreaking approaches of 2017 that has the potential to change the world – may accelerate the development of non-GMO citrus trees that are HLB-resistant.

HLB yellow dragon citrus greening disease has infected orchards in Florida and around the world devastating the citrus crops.

GENETICALLY MODIFIED VS. GENE EDITED

You may wonder why the plants we create with our new DNA editing technique are not considered GMO? It’s a good question.

Genetically modified refers to plants and animals that have been altered in a way that wouldn’t have arisen naturally through evolution. A very obvious example of this involves transferring a gene from one species to another to endow the organism with a new trait – like pest resistance or drought tolerance.

But in our work, we are not cutting and pasting genes from animals or bacteria into plants. We are using genome editing technologies to introduce new plant traits by directly rewriting the plants’ genetic code.

This is faster and more precise than conventional breeding, is less controversial than GMO techniques, and can shave years or even decades off the time it takes to develop new crop varieties for farmers.

There is also another incentive to opt for using gene editing to create designer crops. On March 28, 2018, U.S. Secretary of Agriculture Sonny Perdue announced that the USDA wouldn’t regulate new plant varieties developed with new technologies like genome editing that would yield plants indistinguishable from those developed through traditional breeding methods. By contrast, a plant that includes a gene or genes from another organism, such as bacteria, is considered a GMO. This is another reason why many researchers and companies prefer using CRISPR in agriculture whenever it is possible.

CHANGING THE PLANT BLUEPRINT

The gene editing tool we use is called CRISPR – which stands for “Clustered Regularly Interspaced Short Palindromic Repeats” – and was adapted from the defense systems of bacteria. These bacterial CRISPR systems have been modified so that scientists like myself can edit the DNA of plants, animals, human cells and microorganisms. This technology can be used in many ways, including to correct genetic errors in humans that cause diseases, to engineer animals bred for disease research, and to create novel genetic variations that can accelerate crop improvement.

To use CRISPR to introduce a useful trait into a crop plant, we need to know the genes that control a particular trait. For instance, previous studies have revealed that a natural plant hormone called gibberellin is essential for plant height. The GA20-ox gene controls the quantity of gibberellin produced in plants. To create a breed of “low mowing frequency” lawn grass, for example, we are editing the DNA – changing the sequence of the DNA that makes up gene – of this plant to reduce the output of the GA20-ox gene in the selected turf grass. With lower gibberellin, the grass won’t grow as high and won’t need to be mowed as often.

The CRISPR system was derived from bacteria. It is made up of two parts: Cas9, a little protein that snips DNA, and an RNA molecule that serves as the template for encoding the new trait in the plant’s DNA.

To use CRISPR in plants, the standard approach is to insert the CRISPR genes that encode the CRISPR-Cas9 “editing machines” into the plant cell’s DNA. When the CRISPR-Cas9 gene is active, it will locate and rewrite the relevant section of the plant genome, creating the new trait.

But this is a catch-22. Because to perform DNA editing with CRISPR/Cas9 you first have to genetically alter the plant with foreign CRISPR genes – this would make it a GMO.

A NEW STRATEGY FOR NON-GMO CROPS

For annual crop plants like corn, rice and tomato that complete their life cycles from germination to the production of seeds within one year, the CRISPR genes can be easily eliminated from the edited plants. That’s because some seeds these plants produce do not carry CRISPR genes, just the new traits.

But this problem is much trickier for perennial crop plants that require up to 10 years to reach the stage of flower and seed production. It would take too long to wait for seeds that were free of CRISPR genes.

We first engineered a naturally occurring soil microbe, Agrobacterium, with the CRIPSR genes. Then we take young leaf or shoot material from plants and mix them in petri dishes with the bacteria and allow them to incubate together for a couple of days. This gives the bacteria time to infect the cells and deliver the gene editing machinery, which then alters the plant’s genetic code.

In some Agrobacterium infected cells, the Agrobacterium basically serves as a Trojan horse, bringing all the editing tools into the cell, rather than engineering plants to have their own editing machinery. Because the bacterial genes or CRISPR genes do not become part of the plant’s genome in these cells – and just do the work of gene editing – any plants derived from these cells are not considered a GMO.

After a couple of days, we can cultivate plants from the edited plant cells. Then it take several weeks or months to grow an edited plant that could be planted on a farm. The hard part is figuring out which plants are successfully modified. But we have a solution to this problem too and have developed a method that takes only two weeks to identify the edited plants.

GENETICALLY DESIGNED LAWNS

The shorter lawn grasses on the left (perennial ryegrass) need to be mowed less frequently than their conventional counterpart, shown on the right. The shorter grasses were produced using a traditional plant breeding technique. Yi Li is currently using the CRISPR technique to create grasses of other species that require less maintenance.Yi Li, CC BY-SA

One significant difference between editing plants versus human cells is that we are not as concerned about editing typos. In humans, such errors could cause disease, but off-target mutations in plants are not a serious concern. A number of published studies reported low to negligible off-target activity observed in plants when compared to animal systems.

Also, before distributing any plants to farmers for planting in their field, the edited plants will be carefully evaluated for obvious defects in growth and development or their responses to drought, extreme temperatures, disease and insect attacks. Further, DNA sequencing of edited plants once they have been developed can easily identify any significant undesirable off-target mutations.

In addition to citrus, our technology should be applicable in most perennial crop plants such as apple, sugarcane, grape, pear, banana, poplar, pine, eucalyptus and some annual crop plants such as strawberry, potato and sweet potato that are propagated without using seeds.

We also see a role for genome editing technologies in many other plants used in the agricultural, horticultural and forestry industries. For example, we are creating lawn grass varieties that require less fertilizer and water. I bet you would like that too.

A new tool could be the key to treating genetic diseases and may be the most consequential discovery in biomedicine this century.

It’s challenging to tell a story about something that’s invisible to the naked eye and tricky to explain. But it’s one we undertook, because rarely does a discovery come along that could revolutionize medicine. It’s called CRISPR and it stands for Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR sounds more like a refrigerator compartment than a gene-editing tool, but it’s giving scientists power they could only imagine before – to easily edit DNA – allowing them to reprogram the genetic code of living things. That’s opening up the possibility of curing genetic diseases. Some researchers are even using it to try to prevent disease entirely by correcting defective genes in human embryos. We wanted to see for ourselves, so we went to meet a scientist at the center of the CRISPR craze.

“There are about 6,000 or more diseases that are caused by faulty genes. The hope is that we will be able to address most if not all of them.”

Bill Whitaker: This is CRISPR?

Feng Zhang: This has CRISPR in it.

Bill Whitaker: So– this is what’s revolutionizing science and biomedicine?

Feng Zhang: This is what many people are using– in research — and trying to develop treatments.

Bill Whitaker: That’s wild.

Feng Zhang: Yeah.

That little vial is igniting a big revolution that is likely to change the way doctors treat disease in the future. One of the brains behind it, is baby-faced Feng Zhang.

Feng Zhang speaks with correspondent Bill Whitaker

CBS NEWS

At 36, he’s already a tenured professor at MIT and a scientific celebrity because he figured out a way to override human genetic instructions using CRISPR.

Bill Whitaker: So, the CRISPR is not the liquid, the CRISPR is in the–

Feng Zhang: It’s dissolved in the liquid. There are probably billions of molecules of CRISPR…

Bill Whitaker: Billions?

BOTH: In here.

Feng Zhang: That’s right. And the way we use it is we take the liquid and apply it to cells.

For the last seven years, Zhang has been working on CRISPR at the Broad Institute in Cambridge, Massachusetts. It’s a research mecca brimming with some of the brightest scientific minds from Harvard and MIT on a mission to fight disease. CRISPR is making medical research faster, cheaper, easier. Zhang’s colleagues predict it will help them tackle diseases like cancer and Alzheimer’s.

Bill Whitaker: How many diseases are we talking about that this could be used to treat?

Feng Zhang: There are about 6,000 or more diseases that are caused by faulty genes. The hope is that we will be able to address most if not all of them.

Bill Whitaker: Most if not all of them?

Feng Zhang: That’s the long-term hope.

Bill Whitaker: So we’re talking diseases like Huntington’s—

Feng Zhang: Uh-huh.

Bill Whitaker: Sickle Cell.

Feng Zhang: Yup. ALS—hemophilia.

Eric Lander: I think CRISPR, it’s fair to say, is perhaps the most surprising discovery and maybe most consequential discovery in this century so far.

To understand exactly what CRISPR is, we went to Eric Lander for a quick science lesson. He’s director of the Broad and Zhang’s mentor. He’s best known for being a leader of the Human Genome Project that mapped out all of our DNA, which is like a recurring sequence of letters.

Eric Lander: During the Human Genome Project, we could read out all the human DNA, and then, in the years afterwards, find the misspellings that caused human diseases. But we had no way to think about how to fix ’em. And then, pretty much on schedule, this mind-blowing discovery that bacteria have a way to fix those misspellings, appears.

Bill Whitaker: This comes from bacteria?

Eric Lander: This comes from bacteria. Bacteria, you know, they have a problem. And they came up with a real clever solution. When they get infected by viruses, they keep a little bit of DNA, and they use it as a reminder. And they have this system called CRISPR that grabs those reminders and searches around and says, “If I ever see that again, I am gonna cut it.”

Zhang used that same bacterial system to edit DNA in human cells. Our DNA is made up of chemical bases abbreviated by the letters A, T, C, and G. As you can see in this animation from Zhang’s lab at MIT, a mutation that causes disease reads like a typo in those genetic instructions. If scientists can identify the typo, they can program CRISPR to find it and try to correct it.

Bill Whitaker: You program it? You say–

Feng Zhang: That’s right.

Bill Whitaker: “I’m looking for this string of letters.”

Feng Zhang: Uh-huh.

Bill Whitaker: And the CRISPR will go in, and out of all of the billions and billions and billions of– of letters on your DNA, find the exact ones that you have programmed?

Feng Zhang: That’s right. CRISPR will allow you to– do many different things. You can cut it– to edit it.

Bill Whitaker: So you can snip out the bad part and you can add something that you want as well?

Feng Zhang: That’s right. You can give the cell a new piece of DNA that carries the sequence you want to incorporate into the genome.

Bill Whitaker: You say this so matter of factly. This is amazing.

Feng Zhang: It is pretty cool.

Bill Whitaker: How many other labs around the world are working with CRISPR like this?

Feng Zhang: Many. One of the things that we have been doing is to make the tool available to researchers. To date I think we have gotten it out over– 45,000 times, to 2,200 labs, in 61 countries.

Bill Whitaker: What are they doing with it?

Feng Zhang: They are using it to do everything. A lot of applications of CRISPR. It’s really a Swiss army knife.

Cue the worldwide CRISPR frenzy. At the University of California, scientists used a form of CRISPR to edit mosquitos so they can’t transmit malaria. Their colleagues are modifying rice to better withstand floods and drought. In China, scientists tweaked a gene in beagles to make them more muscular.

A CRISPR vial from Zhang’s lab made its way to Dr. Kang Zhang. He is an ophthalmologist and a professor at the University of California, San Diego and wanted to see what all the hype was about.

Bill Whitaker: What did you think when you first heard of CRISPR?

Kang Zhang: I was a little bit skeptical.

Bill Whitaker: Why skeptical?

Kang Zhang: It worked so well. Too well to be believable.

He decided to experiment on mice with retinitis pigmentosa, a genetic form of blindness. He conducted a vision test using a mouse with the disease.

Bill Whitaker: This is the blind mouse?

Kang Zhang: This is the blind mouse. And– obviously, you can see that he is ignoring the rotating stripes.

His researchers injected CRISPR into the eye of another blind mouse. The CRISPR was programmed to find the main gene associated with the disease and turn it off. It takes three months to see the results.

Kang Zhang: Now, let’s see how he’s responding to the light.

Bill Whitaker: He’s following it around.

Kang Zhang: Yes.

Bill Whitaker: Look at that. You’re sure that he is seeing these lights?

Kang Zhang: This is actually a very commonly used test for vision.

Bill Whitaker: How much of their sight do they recover?

Kang Zhang: About 30, sometimes even 50% of the sight for– for mice.

The next phase of Dr. Zhang’s research is to see how CRISPR works on one of our closer relatives. He sent us this video from his lab in China where he’s studying monkeys with retinitis pigmentosa. The blind monkey ignores the food. He says this monkey was treated with CRISPR and it’s easy to see the difference. Dr. Zhang hopes to try this on humans soon.

If CRISPR is used to treat disease or make a drug it could mean big bucks. The Broad and Feng Zhang hold a primary patent for CRISPR’s use in human cells in the United States. But no technology is developed in a vacuum. Biochemist Jennifer Doudna at the University of California, Berkeley and her team made landmark CRISPR discoveries.

This week, they are challenging Zhang and the Broad in court for the rights arguing in part that Zhang’s advance was derived from her team’s breakthrough. It’s a high stakes battle. CRISPR is projected to be a multi-billion dollar market in a decade.

Bill Whitaker: I think you’re being a little bit modest. I mean this is sparking an incredible boom in biomedicine. And you’re in the center of it.

Feng Zhang: I think there is still really a lot of work that still needs to be done, developing the systems so that they are efficient enough, making sure that they are safe enough, but these are things that– that we’re working hard to– to make possible.

“While it’s not gonna affect somebody who might be dying of a disease today, this is gonna have a real effect over the course of the next decade and couple of decades.”

But, what if it were possible to stop disease from even occurring? That sounds like science fiction, but a team of researchers in Portland, Oregon say with CRISPR, it’s now a reality.

Bill Whitaker: You correct it at the very, very earliest stages of life.

Shoukhrat Mitalipov: Right.

Bill Whitaker: In the womb.

Shoukhrat Mitalipov: Even before the womb.

Manipulating embryos has been the focus of Shoukhrat Mitalipov’s career. He runs the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University. Mitalipov is a maverick. He regularly makes headlines with his innovative, sometimes controversial methods to prevent genetic disease.

Shoukhrat Mitalipov: Preventing is always more effective– so there would be no– no recurrence of new disease. Particularly when we’re talking about heritable– diseases that parents pass to children.

So Mitalipov and an international team of scientists decided to use CRISPR on human embryos to correct a single genetic mutation that causes a deadly heart disease called hypertropic cardiomyopathy.

They got healthy eggs from donors and sperm from a man who carries the disease. At the same time the eggs are fertilized, they also get an injection of CRISPR. Mitalipov enlarged the microscopic procedure over three hundred times so we could see it.

Shoukhrat Mitalipov: Here we have our pipette with sperm inside, which has been already exposed to CRISPR. And this is a egg. And so what we need to do is pierce through, and then we break membrane. And now –

Bill Whitaker: Release the sperm into the egg.

Shoukhrat Mitalipov: Yeah. And now this is the sperm coming in.

Bill Whitaker: Wow.

Shoukhrat Mitalipov: Now it’s inside there.

Bill Whitaker: Just like that, that egg has been CRISPRed?

Shoukhrat Mitalipov: CRISPRed, fertilized.

Bill Whitaker: And you have changed the genetic destiny of that embryo.

Shoukhrat Mitalipov: Yes, we believe so.

These embryos will never be implanted, but they are grown in an incubator for three days and then checked to see if they carry the disease mutation.

Normally, 50 percent would. Mitalipov says with CRISPR, 72 percent were free of the mutation that would cause the heart disease.

Bill Whitaker: This is a huge– advance in science and medicine.

Shoukhrat Mitalipov: We hope so. I think we– we’re still kind of in the early stages. I wouldn’t say that we are ready to– to go to clinics now.

He knows his results have to be replicated by an outside lab before they’re accepted by the scientific community. But if they hold up, one day CRISPR could be used to help families that have been plagued by inherited disease for generations.

Bill Whitaker: Is that what drives you?

Shoukhrat Mitalipov: Yes. Of course, it’s a suffering of children, but also the guilt the parents have at saying, “I passed it to my child.” So it’s like, “I caused this disease.” And I think now, we have a tool where we could help these families.

Mitalipov wants to use CRISPR to eliminate disease, but the concern is his research has created a blueprint for less scrupulous doctors to design human beings – to edit embryos to make babies that are smarter, taller, stronger. Mitalipov says that’s not even possible right now.

Bill Whitaker: Your critics say that you’re playing God.

Shoukhrat Mitalipov: I think– you could say to– to every treatment that they– humans and doctors develop that– we– we’re playing God. God gave us brains so we could find a way to eliminate suffering of human beings. And if that’s– you know, playing God, I guess that’s the way it is.

Bill Whitaker: So what do you think about editing an embryo to prevent disease?

Feng Zhang: We don’t really understand how complicated biology is. There’s a gene called PCSK9. If you remove PCSK9, you can reduce cardiovascular disease, heart attack– risks significantly. But it also has been shown recently to increase risk for diabetes. So how do you make the judgment call between these tradeoffs? And there will likely be other—impacts we haven’t yet identified. So I think we need to wait and be more cautious.

Eric Lander: I don’t think we’re close to ready to use it to go edit the human population. I think we’ve gotta use it for medicine for a while. I think those are the urgent questions. That’s what people want right now, is they want cures for disease.

Those urgent questions might soon be answered. A small clinical trial, the first in the U.S. using CRISPR to target certain types of cancer, is now enrolling patients.

Eric Lander: I wanna always balance hope versus hype here. While it’s not gonna affect somebody who might be dying of a disease today, this is gonna have a real effect over the course of the next decade and couple of decades. And for the next generation, I think it’ll be transformative.

The Florida citrus industry is having their worst harvest in 73 years, and scientists at the University of Connecticut are stepping in to help.

The poor harvest is in part because of damage from Hurricane Irma, but the devastation started long before that. A disease known as citrus greening has been wreaking havoc for years. UConn researchers are working on a solution.

“Our hope is that we can modify endogenous genes in citrus to create the greening disease’s resistance,” explained University of Connecticut scientist Dr. Yi Li.

Gene editing is often discussed in terms of medical advancements and new health treatments. But gene editing can also benefit the food we eat and agriculture as well. Some of the latest developments are happening in Connecticut.

Florida citrus crops have been falling victim to the greening disease since 2005. The contagious disease is spread by a bacteria found in insects feeding off of citrus crops. The bacteria grows and spreads throughout the trees. But the process is slow – it can take up to five years after a tree is infected for it to show signs of damage. As of today, 75 percent of the Florida citrus crops have been wiped out by this quickly spreading disease that has also made its way to crops in Texas and California.

The UConn scientists are working in conjunction with the University of Florida to find a cure.

“We are basically the technology development lab,” Li said. “And then once we develop the technology people in Florida our collaborators are going to use our technology to genetically modify citrus genome.”

These small, targeted changes to an organism’s original genes produce a specific beneficial result. These genetic alterations can provide plants and animals with beneficial characteristics, just like the disease resistance seen in the citrus crops.

Helping the Florida citrus crop is only part of what’s being done here in the lab. Li and his team have also been implementing their gene editing technique on landscaping products that could soon be used in your own backyard. Their latest project? Slow growing grass.

“We started to breed them to develop these traits that we thought would be beneficial to lawn owners, homeowners, and commercial lawn care people,” explains PhD student Lorenzo Katin-Grazzini, “Such as slow growth to drastically reduce the mowing time that’s needed to really just save cost and time and energy associated with turf grass management.”

Li has also created a genetically modified burning bush, a plant often found in New England that spreads rapidly. Where it grows nothing else can, decreasing the diversity in our forests.

“They either don’t produce seeds or produce very few seeds as such that the birds cannot spread them anymore because there are no seeds,” Li said. “So we hope that those plants are going to be released through horticulture in the next two to three years.”

But the lab at UConn isn’t stopping there.

“I do want to work with more ornamental plants,” Li said. “Particularly invasive plants because I do think that has a huge impact on biodiversity on our environment so if we can use gene editing technology to make that non-invasive that’s what I would like to work on.”